Optical transmitter modules are important components for data communications. The module often includes a light emitting device, a light guiding structure and an external optical interface. In this kind of device, a constant optical output is essentially to maintain the quality and stability of the data transmission. However, the optical output power of light emitting devices, such as vertical cavity surface emitting lasers (VCSELs), could be compromised by effects such as the change in the ambient temperature, the aging of the device, etc. In order to maintain a constant optical output, some form of power control is often needed.
Such control is typically done by a feedback circuit control of the output power of the light emitting device during operation. This output power is measured and fed back to the main driver to control the current supplied to the light emitting device, thereby adjusting its optical power output.
Previous attempts to monitor the power of a light emitting device involve the incorporation of an optical sensor alongside the substrate of the light emitting device, which introduces complexity into processing of light emitting device.
The above description of the background is provided to aid in understanding the optical transmitter module, but is not admitted to describe or constitute pertinent prior art to the optical transmitter module, or consider any documents cited herein as material to the patentability of the claims of the present application.